1. Field of the Invention
This invention relates generally to flexible expansion joint materials for use in industrial flue ducts and other like applications, and is concerned in particular with an improved single membrane expansion joint material capable of withstanding elevated temperatures on the order of 500-1000.degree. F. and higher.
2. Description of the Prior Act
Flexible expansion joints permit interconnected sections of large flue ducts to undergo relative shifting in response to thermal changes. This is particularly important where normal operating temperatures range from 600-800.degree. F.
Fluoroplastic/fiberglass composites adequately serve as expansion joint materials in operating temperature ranges below about 500.degree. F. Higher temperatures cause thermal deterioration, thereby necessitating additional layers of insulation, usually uncoated fiberglass. The additional insulation layers are bulky, friable, difficult to install, and prone to sag when inverted. Sagging reduces insulating quality and interferes with the flow of gases through the duct.
A primary objective of the present invention is the provision of a single membrane expansion joint material capable of withstanding exposure to high temperature gases without undergoing thermal deterioration.
Companion objectives of the present invention include the provision of an expansion joint material which is relatively compact, easy to handle and install, with an insulation layer which remains intimately bonded to adjacent components of the composite, irrespective of the physical orientation of the material during installation and subsequent use.